Damper TouchWeight

[jolly roger]

Greeting Del,
                   I just checked a new Hamilton and P22.  It takes 85gms
just to start decompressing the felt at mid C  The weights were placed on
the key slowly and carefully to take acceleration one of the equation, as
it would greatly effect the point of inertia at pick up.    So I don't
think 90gms is out of line, depending on how you placed the weights.

Damper levers are very prone to sliding friction problems as you know.  So
attention to detail with spoon and sping, along with the condition of the
felt is important.

The most common problem with verticals is damper timing and damper follow.
 Follow I like 1/8" for wound strings, and a little better than 1/16" for
the plain wire. Damper movement to start at half dip.

As a point of interest, our Yamaha digital pianos have a touch weight of
85gms from the begining of key movement. Yet pianist never complain that
they are heavy.   Go figure.  <G>
This leads me to believe that subliminally the piano player may feel damper
pick up. It is more the manner of pick up that counts.  Is it smooth? Does
the key have enough velocity so the pick up inertia is not felt. (timing)
Is there enough follow? so the decompression of felt is also helping to
mask and sudden changes in touch.

I am half way through a new series for the Journal, Understanding vertical
dampers, as a companion to my grand series.
This will also include many aspects of redesign.  ( Installing Yamaha U3
damper systems in any larger vertical.) 
Now if I could only fully understand them myself.  <G>

Hope this helps.
Roger





At 08:32 AM 8/8/01 -0700, you wrote:
>
>----- Original Message -----
>From: "Tom Driscoll" <tomtuner@mediaone.net>
>To: <pianotech@ptg.org>
>Sent: August 08, 2001 9:00 AM
>Subject: Re: Damper TouchWeight
>
>
>>
>> From: Delwin D Fandrich <pianobuilders@olynet.com>
>> Subject: Re: Damper TouchWeight
>>
>>
>> Del ,
>>            Would the weights be placed on the damper heads?  How heavy
>and
>> how installed?
>> Thanks, Tom Driscoll
>> ------------------------------------------------------
>
>Placing them on the damper head would be ideal but I don't know how you
>would do it and keep them from interfering with things and/or coming loose.
>With our upright we solved the problem by switching from wood damper barrels
>to brass barrels (both from Renner). Obviously this would be overkill in
>most simple damper ringing cases.
>
>Much more practical is locating them on the damper wire. Exactly how this is
>done depends on the types of fishing that go on in your area and the types
>of leads available. The best I've seen so far is a relatively long
>football-shaped lead with a slit through to a longitudinal hole running
>through the middle. They come in several different sizes. As I recall from
>the last time this came up, the store I visited carried three sizes that
>were physically practical. I would carry a couple of each of these for trial
>use.
>
>How heavy? That depends on the piano and the extent of the damping problem.
>Make sure the dampers are mechanically working the way they should be
>working--that is, spoons smooth and shiny, spoons properly adjusted, action
>centers free, damper felts in reasonable condition, etc. Then back off on
>the damper springs until they exert only a reasonable amount of force
>against the string--no, I don't have a measurement for this, I go by feel.
>One day I'll measure it. Or I'll ask Roger. But you shouldn't really feel
>the damper kick in under anything above pianissimo.
>
>Now listen to the piano. Find a couple of real ringers--the kind you would
>normally really stiffen the spring on--and clip on the lightest of your
>leads. Now listen again. If that didn't quite do it, go up a size and listen
>again. Remember that there is a certain amount of interactivity here. In
>general, use the larger weights toward the lower bass and the smaller
>weights toward the upper bass. Don't forget the hacked-up mini-dampers just
>above the bass/tenor crossover.
>
>Once you've selected the appropriate leads, put a couple of drops of PVC-E
>or white glue in the hole, slip it over the wire just above the wood lever
>and lightly crimp it in place. Don't use CA glue. It won't stand up to this
>kind of load. The glue is really only there to keep the lead from rattling
>and/or buzzing.
>
>Once the damper leavers are properly mass-loaded, you'll find that much less
>damper spring pressure is needed for good damping.
>
>There is more on this issue in the PT Journal. See
>The Designer's Notebook
> Dampers—Why Are They So Darn Much Trouble?
>December, 1995
>in which I discuss the need for such mass-loading but not much on how to do
>it.
>
>Del
>